New insights into Holocene marine terrace development caused by seismic and aseismic faulting in the Coastal Range, eastern Taiwan

The Coastal Range in eastern Taiwan, which has resulted from arc-continent collisions, involves well-developed Holocene uplifted marine terraces along a 140-km long stretch of the coast. This is the first study that unraveled the aseismic generation of marine terraces associated with coseismic uplift along the creeping fault. We organized DEMs/LiDAR mapping and field surveys to obtain detailed and systematic measurements of the inner and outer edges and wave-cut platform elevations along thirty-three stream profile transects, allowing us to locate the bedrock profile. Spatial and temporal variations in the 14C age are characterized by an offlapping built feature of significant seaward younging trend of ages across the marine terrace, caused by aseismic and coseismic uplift. Thus, heights of the bedrock riser and platform are caused by coseismic (large earthquake) and aseismic plus moderate coseismic vertical deformations during a large earthquake cycle, respectively. This indicates that each terrace duration and paleoshoreline ages can be used to infer the recurrence interval and the timing of large earthquake events, respectively. Results of the age of the paleoshoreline indicate six paleoseismic events at ∼8500, ∼6300, ∼4800, ∼3400, ∼1700, and ∼700 yr BP. This implies that the Chihshang creeping Fault could be capable of producing large earthquakes (greater than M7) at millennial time scales associated with larger coseismic deformations. The creep faulting associated with seismic and aseismic uplift is a dominant process constraining the Holocene marine terrace evolution. © 2020 Elsevier Ltd